Pre-coronizing treatment for desizing glass fabric

ABSTRACT

A WET DESIZNG TREATMENT FOR GLASS FABRIC PRIOR TO CORONIZATION OF THE FABRIC EMPLOYING A SOLUTION CONTAINING PEROXYDISULFATE OF A PEROXYDIPHOSPHATE IN COMBINATION WITH A NONIOIC WETTING AGENT. A SURPRISINGLY STRONGER GLASS FABRIC IS OBTAINED AFTER CORONIZATION WHEN THE FABRIC IS DESIZED ACCORDING TO THE PROCESS PROVIDED.

United States Patent ABSTRACT OF THE DISCLOSURE A wet desizing treatment for glass fabric prior to coronization of the fabric employing a solution containing peroxydisulfate or a peroxydiphosphate in combination with a .nonionic wetting agent. A surprisingly stronger glass fabric is obtained after coronization when the fabric is desized according to the process provided.

This invention concerns desizing of glass fabric employing a wet process treatment prior to coronization of the glass fabric.

The application of suitable size to glass fibers is important especially when the glass fibers are to be subjected to textile processing. The size must lubricate the fibers to minimize the effects of fiber-fiber friction and hold the individual filaments together in the strand. At the same time the size must not make the strands adhere to packaging or processing equipment. Dextranized starch gum, gelatin, polyvinyl alcohol, hydrogenated vegetable oils and nonionic or ionic detergents are commonly used as sizing material.

Often, glass fabrics are combined with other materials such as coatings, resins and dyes. In order to insure an effective union of the glass with these materials, it is necessary to remove the sizing that was applied to the glass during the manufacture of the fabric. This is conventionally done by heat cleaning the fabric at high temperatures, usually about 650 C. to burn away the organic sizing material.

Glass fabrics are usually subjected to a coronization treatment which is a finishing treatment that has significant effects on glass fibers and fabrics used for textile applications. Strains introduced during processing and production of glass yarns and fabrics are relieved during the coronization treatment and the glass fabric becomes dimensionally stable. Furthermore, the coronization increases the fabrics resistance to abrasion, water-repellency, crease resistance, flexibility and improves the handle to an impressive degree. Coronization also makes possible the effective coloration of glass fabrics.

The coronization treatment of the glass fabric takes place at temperatures of about 650 C. and therefore the desizing of the fabric and the coronization of the fabric are usually done simultaneously because both require approximately the same temperature of about 650 C. However, the glass fiber is weakened during the desizing and coronizing of the fabric by heat treatment at about 650 C.

This invention makes it possible to obtain the benefits of coronization and desizing without the weakening of the fabric to the degree associated with combined desized and coronizing by heat treatment.

A low temperature, wet, pre-coronizing treatment for desizing glass fabrics is provided by this invention which comprises treating sized glass fabrics by dampening the fabric with suflicient aqueous desizing solution containing a nonionic wetting agent and a peroxygen chemical selected from the group consisting of a watersoluble peroxydiphosphate or a water-soluble peroxydisulfate to result in between 0.1% and 2.0% peroxygen chemical and between 0.025% and 0.1% wetting agent on the fabric based upon the weight of fabric being treated, maintaining the dampened fabric at a treatment temperature of from 160 F. to the boiling temperature of the treatment solution for between 5 seconds and 240 seconds, and then washing the fabric usually with water to substantially remove the desizing solution and size.

Specifically, the desizing process comprises dampening glass fiber preferably as a fabric, with an aqueous treatment solution containing a peroxygen chemical and a nonionic wetting agent, heating the dampened fibers to a process temperature of 160-275 F. preferably about 212 F. for at least five seconds and then washing the fabric whereby a high quality desized glass fabric is obtained.

Dampening the fabric requires contacting the fabric with suflicient solution so that at least 0.1% peroxygen chemical is in contact with the fabric based upon the weight of the fabric being treated. Furthermore, there must be sufficient solution on the fabric as a result of dampening to result in at least 0.025% of the nonionic wetting agent in contact with the fabric based upon the weight of the fabric being treated. The dampening of the fibers is carried out by conventional means for example they can be immersed in a bath of the desizing solution, removed from the bath and squeezed to remove excessive solution. Many other means for dampening fabrics are well known to those skilled in the fabric treating art.

The concentration of wetting agent and peroxygen chemical in the desizing solution can vary greatly so long as their concentrations in combination with the amount of desizing solution on the fabric results in the above amounts based upon the weight of fabric being treated.

The desizing solution is an aqueous solution containing (1) a peroxygen chemical selected from the group consisting of a water-soluble peroxydiphosphate or a water-soluble peroxydisulfate, and

(2) a nonionic wetting agent.

Any water-soluble peroxydiphosphate or peroxydisulfate salt can be used in practicing the present invention. Preferred are the metallic or ammonium salts of peroxydiphosphates or peroxydisulfates with tetrapotassium peroxydiphosphate, sodium peroxydiphosphate and sodium peroxydisulfate being particularly preferred.

The preferred concentration of peroxygen in the desizing solution is between 0.1% and 25% with about 10% being particularly preferred. The preferred concentration of nonionic wetting agent in the treatment solution is between 0.025 to 2% with about 0.13% particularly preferred.

Nonionic wetting agents such as Triton X are well known in the art and suitable for practicingthe present invention. Other nonionic wetting agents suitable for use include alkylphenylethylene oxide condensates in which the alkyl substituent may vary from C through C carbon atoms and the number of moles of condensed ethylene oxide units varies from 1 to 100 per mole of alkyl such as isooctylphenyl polyethoxy ethanol or dodecylphenyl polyethylene glycol ether; polyoxyethylene thioethers; propylene oxide-ethylene oxide condensates such as are described in U.S. Pat. 2,674,619; fatty acid alkanolamides in which the fatty acid constitute may vary from C through C carbon atoms, such as lauric acid alkanolamide; alkyl poly(ethyleneoxy) ethanols in which the alkyl radical may vary from C through C carbon atoms and the moles of condensed ethylene oxide may vary from 1 to 100 per mole of alkyl such as tridecyloxy poly- (ethyleneoxy) ethanol, or the ethylene oxide condensate of stearyl alcohol containing about 10 moles of ethylene oxide per stearyl mole; and the polyhydroxyalkyl fatty acid esters such as glycerol monooleate or sorbitan-stearate.

The processing temperature preferably is about 212 F. and is normally obtained by contacting the dampened fabric with steam at ambient pressure. However, temperatures somewhat lower than 212 F. that is down to about 160 F. can be employed although processing time increases as the temperature decreases below 212 F. Temperatures above 212 F. can be obtained by performing the process in a pressure type vessel in which boiling point temperatures as high as about 275 F. can be obtained. Pressure type vessels for treating fabrics are well known, such as Vapor-Lock. At elevated temperatures above 212 F. processing time is decreased.

Washing the fabric after treatment is important since washing carries away the solubilized size and therefore completes the desizing. 'Washing is usually done by rins ing the fabric with warm water with or Without additives. Any of the many known methods for Washing fabrics is suitable.

Following washing, the fabric is dried because introducing wet fabric into a high temperature coronizing treatment is dangerous and makes coronization temperature control very difiicult. After drying, the fabric can be coronized according to conventional methods.

The effects of the desizing solution upon the fabric are improved by adding some sodium hydroxide or other suitable alkali to the solution so that after dampening there is at least 0.1 part and preferably about 0.25 part of alkali per 100 parts of fabric being treated. Other suitable alkalies include potassium hydroxide, sodium carbonate, potassium carbonate, ammonia and the like. The concentration of alkali in the desizing solution can vary greatly so long as the concentration of alkali when used in combination with the amount of desizing solution on the fabric results in at least 0.1 part alkali per 100 parts of fabric being treated.

The term glass fabric as used herein refers to textile fabrics made from glass fiber which fiber is spun from molten glass. There are many known methods of spinning fibers from glass such as the centrifugal, jet or rod drawing processes. Suitable glasses for the production of glass fibers include a wide range of materials which are made by fusing together one or more of the oxides of silicon, boron or phosphorus with certain basic oxides such as sodium, potassium, magnesium, or calcium oxide and the fused product is cooled rapidly to prevent crystallization from taking place. Typical glasses. used for producing glass fibers are known as type B (silicon silicate glass) and type C glass (borosilicate glass).

The following testing procedures were used in all of the examples.

(1) Determination of available removable size content of greige, glass fiber fabrics.-A sample of greige fabric was dried to constant weight and the sample was then placed in a muffle furnace at 1200 F. for minutes to burn off all size materials. From the difference in the sample weight before and after burning the percent of available removable size was calculated based upon the assumption that the loss of weight was due completely to the burning off of available size.

(2) Determination of efliciency of size removaL-A sample of greige fabric was dried to constant Weight and then subjected to the pre-coronizing desizing treatment provided by this invention, washed with water and then dried to a constant weight. From the difference in weight before and after the desizing treatment, the percentage of size removed was determined. The percent of size removed divided by the percentage of available removable size times 100 equals the efiiciency of size removal.

(3) Determination of bursting strength-Samples of treated fabric were tested for strength employing Owens Corning Fiberglas Standard test method #DF511 and using a Mullens Diaphragm Bursting Tester.

In all of the examples sized glass fabric was used. All

proportions used herein are based upon weight unless indicated otherwise.

EXAMPLE 1 A sample of commercial sized glass fabric containing 2.5% available removable size was cut into three pieces. The size on the fabric contained a modified cornstarch, cationic softener, and hydrogenated animal stearate. The first piece was saturated with a solution containing sufficient nonionic wetting agent to result in 0.1% wetting agent on the fabric basedupon the'weight of fabric being treated. The second piece of fabric was saturated with solution containing sufficient nonionic Wetting agent and sufficient peroxydisulfate to result in 0.1% wetting agent and 0.5% peroxydisulfate on the fabric based upon the weight of fabric being treated. The third piece of fabric was saturated with sufficient solution containing nonionic wetting agent and tetrapotassium peroxydiphosphate to result in 0.1% wetting agent and 0.5% peroxydiphosphate on the fabric based upon the weight of fabric being treated. All three pieces of fabric were steamed at about 212 F. for 15 seconds and then washed for 1 minute with distilled water at 155 F. The samples were then analyzed to determine the efficiency of the size removal. The piece of fabric treated with a solution containing only Wetting agent had 65% size removed; while the piece treated with wetting agent and peroxydisulfate had size removed. 'Ilhe piece treated with wetting agent and the peroxydiphosphate had 88% size removed.

EXAMPLE 2 A sample of commercial sized glass fabric containing 2.1% available removale size was cut into three pieces and the procedure of Example 1 was repeated. The size on the pieces of fabric used in this example contained modified starches, cationic lubricant, hydrogenated vegetable oil, and gelatin. The piece of fabric treated with the solution containing only nonionic wetting agents had 74% available size removed. The piece treated with solution containing nonionic wetting agent and peroxydisulfate had 91% available size removed. The piece treated with a solution containing nonionic Wettingagent and peroxydiphosphate had 91% available size removed.

EXAMPLE 3RUN 1 A sample of commercial glass fabric weighing 4.9-5.0 oz./ yd. and containing 2.4% available removable size was desized under mill conditions as follows: 15 yards of fabric were padded with sufficient solution containing-sodium peroxydisulfate, nonionic wetting agent, and sodium hydroxide to result in 1% sodium peroxydisulfate, 0.1% nonionic wetting agent and 0.25% sodium hydroxide respectively on the fabric based upon the weight of'fabric being treated. The fabric Was then steamed at about 212 F. for seconds and washed with approximately F. hot water. The desized'fabric was then weave-setin a coronizing' unit for 7 seconds at 1170 F. The'coronized fabric was then tested for "percent strength loss (calculated from the difference between the bursting strength of the weave-set fabric versus the bursting strength of the untreated fabric. The fabric had a 13.8%stren'gth loss after desizing and coronizing. v r

, EXAMPLE 3COMPARATIVE RUN 1 of run 1. v

5 What is claimed is: 1. A process for treating glass fabric to provide a stronger fabric after coronization comprising:

dampening sized glass fabric with suflicient aqueous desizing solution containing a nonionic wetting agent and a peroxygen chemical selected from the group consisting of a water-soluble peroxydiphosphate and a water-soluble peroxydisulfate to provide 0.1% to 2.0% of said peroxygen chemical and 0.025% to 0.1% of said nonionic wetting agent on the fabric based upon the weight of fabric being treated;

heating and maintaining the dampened fabric at a temperature of from 160 F. to the boiling temperature of the solution on the fabric for 5 seconds to 240 seconds;

washing the fabric so treated to substantially remove said desizing solution and size; and coronizing the washed fabric.

2. The process of claim 1 in which the peroxygen is tetrapotassium peroxydiphosphate.

3. The process of claim 1 in which the peroxygen is sodium peroxydiphosphate.

4. The process of claim 1 in which the peroxygen is sodium peroxydisulfate.

5. The process of claim 1 in which the solution contains sufiicient alkali to result in about 0.25% alkali in contact with the fabric based upon the weight of fabric being treated.

References Cited UNITED STATES PATENTS 2,674,549 4/1954 Balz 134-2 3,634,024 1/1972 Yelin 8-138 2,173,040 9/1939 Miiller 8--138 MORRIS O. WOLK, Primary Examiner D. LOVERCHECK, Assistant Examiner US. Cl. X.R. 

